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A075815
Palindromic odd composite numbers with an odd number of prime factors (counted with multiplicity).
1
99, 171, 333, 343, 363, 555, 575, 595, 747, 777, 909, 969, 1001, 1221, 1331, 1551, 1771, 3333, 3553, 5335, 5445, 5555, 5665, 5775, 5885, 5995, 7337, 7557, 7667, 7777, 7887, 9009, 9339, 9559, 9669, 9779, 9889, 11211, 11511, 11711, 11811, 12121
OFFSET
1,1
LINKS
EXAMPLE
5445=3^2*5*11^2 and 5555=5*11*101 are palindromic, odd, composite and have an odd number of prime factors.
MAPLE
test := proc(n) local d; d := convert(n, base, 10); return ListTools[Reverse](d)=d and type(numtheory[bigomega](n), odd) and not isprime(n); end; a := []; for n from 1 to 13000 by 2 do if test(n) then a := [op(a), n]; end; od; a;
MATHEMATICA
Select[Range[9, 13000, 2], PalindromeQ[#]&&CompositeQ[#]&&OddQ[ PrimeOmega[ #]]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jan 28 2021 *)
CROSSREFS
Cf. A046389.
Sequence in context: A185498 A126230 A055164 * A075814 A320707 A235228
KEYWORD
nonn,base
AUTHOR
Jani Melik, Oct 13 2002
EXTENSIONS
Edited by Dean Hickerson, Oct 21 2002
STATUS
approved